Let's not forget Laura Bell Bundy. She was the Glinda standby for a few months. (Or was she the GALINDA standby?)
I think I'm going to call FOX to see if they will start a new reality show -- The Elphaba Chronicles. Each individual who has starred as, understudied, stood by for, or sung Defying Gravity in their shower gets to compete to see who is the ultimate Elphaba. This will include a competition to see who can belt the highest note, who can make the cherry picker go to full extension the fastest, who looks the best green, and probably mud wrestling.
". . . POP . . ."